Projected CAP/SAC-CI method with smooth Voronoi potential for calculating resonance states

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Chemistry

Background:

• Accurate calculation of π* resonance states is crucial for understanding molecular electronic properties.
• Previous methods faced challenges in precisely locating these short-lived states.

Purpose of the Study:

• To apply the projected complex absorbing potential (CAP)/symmetry-adapted cluster-configuration interaction (SAC-CI) method with a smooth Voronoi potential.
• To calculate π* resonance states of various small- to medium-sized molecules, including double-bond and heteroaromatic systems.

Main Methods:

• Integration of the projected CAP/SAC-CI method with a recently developed smooth Voronoi potential.
• Extrapolation procedure using the smooth Voronoi potential to determine resonance energies and widths.
• Application to molecules such as acetaldehyde, butadiene, glyoxal, pyridine, pyrazine, and furan.

Main Results:

• The projected CAP/SAC-CI method with the smooth Voronoi potential successfully located π* resonance states.
• Corrected η-trajectories yielded stable resonance energies and lifetimes irrespective of the potential's size parameter (rcut).
• Stabilization behavior of the trajectories was more pronounced with larger rcut values, indicating improved CAP-electron interaction.

Conclusions:

• The combined CAP/SAC-CI and smooth Voronoi potential method is effective for calculating π* resonances.
• Larger cavity sizes (rcut) in the Voronoi potential enhance the stabilization and accuracy of resonance state calculations.
• This approach offers a robust tool for investigating electronic resonances in diverse molecular systems.